import java.util.Scanner;

/**
 * 计算一个浮点数的立方根，不使用库函数。
 * 保留一位小数。
 */
public class CubicRoot {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        while (scanner.hasNext()){
            String s = scanner.nextLine();
            double num = Double.parseDouble(s);
            double low = -20, high = 20, mid;
            mid = (high+low)/2;
            while ((high-low) < 0.01 && Math.abs(mid*mid*mid - num) < 0.01 ){
                mid = (high+low)/2;
                if((mid*mid*mid - num) > 0.01){
                    high = mid;
                }else {
                    low = mid;
                }
            }
            System.out.printf("%.1f%n",mid);
        }
    }
}
